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authorars <asav1410@gmail.com>2020-06-17 15:59:52 +0100
committerars <asav1410@gmail.com>2020-06-17 15:59:52 +0100
commitf665f78155047838dc924634ebe4128f7add5542 (patch)
treefa0b6d2fd4a7b26d7fac2d557066044384d33010 /dev_scripts/sen15901vane.py
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+from gpiozero import MCP3008
+import time
+import math
+
+adc = MCP3008(channel=0)
+count = 0
+"""
+volts key pairs created with the below + known values from datasheet
+ # create voltage divider for use with MCP3008 ADC
+ def volt_div(r1, r2, vIn):
+ vOut = (vIn * r2)/(r1 + r2)
+ return round(vOut,3)
+
+ # calculate vOut values for each wind direction using known resistances from datasheet, 3.3 V from RPi and 4.7K ohm resistor
+
+ resistances = [33000, 6570, 8200, 891, 1000, 688, 2200, 1410, 390, 3140, 16000, 14120, 120000, 42120, 64900, 21880]
+
+ for i in range(len(resistances)):
+ print(resistances[i],volt_div(4700, resistances[i], 3.3))
+
+4.7K resistor
+volts = {0.4: "0.0 N",
+ 1.4: "22.5 NNE",
+ 1.2: "45.0 NE",
+ 2.8: "67.5 ENE",
+ 2.7: "90.0 E",
+ 2.9: "112.5 ESE",
+ 2.2: "135.0 SE",
+ 2.5: "157.5 SSE",
+ 1.8: "180.0 S",
+ 2.0: "202.5 SSW",
+ 0.7: "225.0 SW",
+ 0.8: "247.5 WSW",
+ 0.1: "270.0 W",
+ 0.3: "292.5 WNW",
+ 0.2: "315.0 NW",
+ 0.6: "337.5 NNW"}
+"""
+# 5K resistor
+volts = {1.87: 0.0,
+ 2.04: 22.5,
+ 0.79: 45.0,
+ 0.80: 45.0,
+ 0.88: 67.5,
+ 0.13: 90.0,
+ 0.36: 112.5,
+ 0.24: 135.0,
+ 0.62: 157.5,
+ 0.44: 180.0,
+ 1.44: 202.5,
+ 1.27: 225.0,
+ 2.81: 247.5,
+ 2.76: 270.0,
+ 2.91: 292.5,
+ 2.31: 315.0,
+ 2.59: 337.5}
+
+def getAverage(angles):
+ sinSum = 0.0
+ cosSum = 0.0
+
+ for angle in angles:
+ r = math.radians(angle)
+ sinSum += math.sin(r)
+ cosSum += math.cos(r)
+
+ flen = float(len(angles))
+ s = sinSum / flen
+ c = cosSum / flen
+ arc = math.degrees(math.atan(s / c))
+ average = 0.0
+
+ if s > 0 and c > 0:
+ average = arc
+ elif c <0:
+ average = arc + 180
+ elif s < 0 and c > 0:
+ average = arc + 360
+
+ return 0.0 if average == 360 else average
+
+def getValue(length=5):
+ data = []
+ startTime = time.time()
+
+ while time.time() - startTime <= length:
+ wind = round(adc.value*3.3,2)
+ if not wind in volts: # keep only good measurements
+ print("Unknown value: " + str(wind))
+ else:
+ data.append(volts[wind])
+
+ return getAverage(data)
+
+getValue()